This invention relates to a method of deburring and/or polishing a steel article. More particularly, the invention relates to a method of deburring and/or polishing a steel article which comprises subjecting said article as the anode to the action of a direct current in an electrolyte containing, in addition to one or more electrolytically active (that is, ionizable) constituents, at least one polyhydric alcohol for controlling the viscosity of the bath. The method involves the use of a bath voltage (that is, a voltage between the anode and the cathode) in the range of 4 to 25 volts and a current density in the range of 2 to 50 amperes per square decimeter.
A deburring method of the kind above set out is required to produce a satisfactory burr removing action while removing as little material as possible from the even areas of the article. In electrolytic polishing (also referred to as electrolytic brightening), some slight removal of material from the surface of the article is, of course, unavoidable. The articles treated should present a uniform and attractive appearance throughout their surface, with no remaining roughness.
The practical applicability of the method and the total costs of the treatment very much depend on the extent to which various practical desiderata can be satisfied. The time required for the treatment of an article should be short. The useful life of the bath solution should be long. The bath temperature required should not be undesirably high, preferably not substantially in excess of room temperature. The bath as well as the vapours given off thereby should not be poisonous or otherwise constitute a health hazard. Spent bath liguids should be disposable simply and cheaply.
Known methods of the general kind above specified entail the use of baths containing substantial proportions of one or more strong acids. Baths of this kind, being strongly erosive and dangerous, require a well-trained personnel as well as shops equipped with facilities for the exhausting and neutralizing of the escaping vapours. Also, the useful life of the baths is comparatively short.
The present invention has for its general object to provide a method of the kind above specified and a bath composition therefor, which have improved properties in at least some of the respects above referred to. A more special object is the provision of a method and an electrolyte bath therefor which require a minimum of safety measures and which can be handled by personnel having no or little special training. Still another object is the provision of a bath which has a long useful life and, when spent, can be disposed of easily.